#ifdef GL_ES
precision mediump float;
#endif

// uniform vec2 u_resolution; // 画布尺寸
// uniform vec2 u_mouse; // 鼠标位置
// uniform float u_time; //时间


uniform float u_time;

void main() {
    gl_FragColor = vec4(abs(sin(u_time)), 0.0,0.0,1.0);
}


